It's not cutting. If you didn't have a fast pass and get in line when it is posted at 45 mins, then you are waiting for 45 minutes with or without the fast pass. Just that with fast pass, there are only 100 people in front of you in queue without it there are 1000. Stop equating fast pass to cutting. That is disingenuous.
I think you're missing the point... If you are in next in line in the standby line and 100 people pass you to get on the ride first, your boarding is delayed waiting for all of those people. That is going on throughout your entire wait, therefore the standby line is artificially inflated because you are letting the "line cutters" eat up most of the ride capacity.
As has been explained, if everyone who had a FP was not allowed to also get in a standby line, that'd be one thing. But now people are taking up two spots in line - on in a virtual way via FP and one actual place standing in a regular line.